Fluid bags with an integral tuble-like passageway for cooperation with a peristaltic pump device

ABSTRACT

A bag is provided for containing a liquid intended to be supplied in a controlled manner to some other site, for example to a medical patient. The main bag portion has a pair of overlying side walls joined together around their edges, the side walls having integral extensions which together define an outlet region in communication with the interior of the main portion of the bag. The extensions are bonded together to define a tube-like passageway extending throughout the outlet region from the interior of the bag. The extensions are adapted to permit the connection thereto of a peristaltic pump device co-operable with the tube-like passageway to control the out-flow of liquid from the bag.

[0001] This invention relates to a bag for containing a liquid, and inparticular to a bag which is adapted for use in circumstances where agradual outflow of the contained liquid is required.

[0002] Though the invention is primarily concerned with a bag forcontaining a sterile liquid for use in the medical industry, as a sourceof liquid for supply to a human body by way of an intravenous catheter,it will be appreciated that the invention is not to be regarded aslimited to that use and may find application in other industries.Nevertheless, the invention will be described hereinafter solely withreference to its use for healthcare.

[0003] In all branches of healthcare, bags for the supply of liquids tothe human (or even animal) body are widely used, by means of intravenousintroduction. Mostly those liquids are supplied by suspending the bagabove the body and allowing the liquid to run through a restriction toan intravenous catheter inserted into the patient's body. Therestriction usually is adjustable, to permit the required flow rate tobe set by observing the rate at which drops of the liquid fall throughthe restriction into a chamber immediately therebelow. Unfortunately, itis not possible to achieve accurate flow rates which can be maintainedfor a relatively long period of time. In particular, also temperatureeffects can affect the liquid viscosity and the flow rate through therestriction. Moreover, if a rate of flow higher than an observable driprate is required, some other technique must be employed for determiningthe actual flow rate.

[0004] In order to overcome the above disadvantages, it is known toposition a liquid bag within a bag squeezer having a piston which ispower driven at a controlled rate, so as to drive liquid from the bag.Though such squeezers are known in the healthcare industry, in generalthey are not widely used since they tend to be unreliable in operation,and complete emptying of a bag is very difficult with such equipment.

[0005] If a flow rate higher than that which con be achieved with a dripis required, with good accuracy, it is known to employ a peristalticpump having a flexible tube which is arranged in the pipe from the bagto the catheter. The operation of the pump may be closely controlled inorder to achieve a desired flow rate through the tube, conducting liquidfrom the bag to the patient's body. After use, the cleaning of the pumptube is time consuming, or in the alternative, if the tube is scrapped,significant costs are involved, since the pump requires a tube of known,controlled characteristics. Further, it is necessary to have multiplejunctions in the pipe from the bag to the catheter, leading to thepossibility of disconnection should the patient move, leaks, and maybeeven allowing the introduction of bacteria into the pipe.

[0006] The present invention aims at addressing the above issues andallowing the use of a peristaltic pump in association with a bagcontaining a liquid intended to be supplied over a period of time to apatient, at a known and controlled flow rate.

[0007] Accordingly, one aspect of this invention provides bag forcontaining a liquid intended to be supplied in a controlled manner tosome other site, comprising a main bag portion having a pair ofoverlying side walls joined together around their edges thereby todefine a reservoir for the liquid, the side walls having a pair ofintegral overlying extensions projecting from the conjoined edges so asto form a pump area projecting from one side of the bag, the extensionsbeing bonded together to define a tube-like passageway having a sectionof part circular form and extending from the interior of the reservoirfor fluid to an outlet region at an edge of the pump area, theextensions being profiled and adapted to permit the connection theretoof a peristaltic pump device having pump members driven around acircular path centered on the centre of said section of the passageway,whereby the connection of the peristaltic pump device to the extensionsand co-operable with the passageway controls the out-flow of liquid fromthe reservoir.

[0008] The major part of the bag of the present invention may beessentially the same as the bags already widely in use throughout thehealthcare industry, for containing liquids to be supplied intravenouslyto patients. However, at the lower end of such a bag (considering thebag when suspended for the supply of liquid) the two side walls definingthe bag have integral overlying extensions which are profiled andadapted to permit the direct connection thereto of a peristaltic pumpdevice co-operating with the tube-like passageway formed by the walls ofthe bag extension. During manufacture of the bag, the sheets which formthe side walls and the extensions may be given the required flexibilityproperties for co-operation with the peristaltic pump, so obviating theneed for the use of a special tube intended expressly for use with aperistaltic pump.

[0009] The passageway is formed by bonding together the two overlyingextensions in such a way that the passageway extends across thoseextensions, from the main portion of the bag to an edge of theextensions where a conventional intravenous supply pipe may be connectedto the passageway. For this purpose, a connector socket or spigot may beprovided as a part of the bag, which socket or spigot may connectdirectly to an intravenous supply pipe leading to a catheter. Thebonding together of the overlying extensions and also the provision of asocket or spigot, to form the tube-like passageway therebetween, may beperformed by use of heat sealing, sonic sealing or RF sealingtechniques.

[0010] The passageway has a part-circular form, so as to be suitable foruse with a rotary peristaltic pump having pumping members engaged withthe passageway and running in a circular path overlying thepart-circular form of the passageway, to drive fluid therealong.

[0011] In a particularly preferred form of bag of this invention, thebag has extensions which define a passageway having a linear firstportion leading from the bottom of the bag (considering the normaldisposition of the bag when suspended for use) into the extensions, apart-circular second portion of constant radius and extending for some300° to 340° of arc, a part-circular third portion doubled back toextend around part of the second portion, and a linear fourth portionleading from the end of the third portion to an common edge of theextensions. In a modification of this, the order of the second and thirdportions is reversed.

[0012] The overall shape of the extensions may have any required shapeto permit the connection thereto of a peristaltic pump, having regard tothe design of the pump itself. Typically, there will be flanges to bothsides of the passageway, together with apertures through the flanges,for registration purposes with corresponding projections provided on thepump. Such a pump may have a base plate including such projections andon which the extensions of the bag are placed, and an actuator carryingthe peristaltic pumping members together with a drive arrangementtherefor which actuator may be attached to the base plate so clampingthe bag extensions therebetween. This invention extends to a bag for thesupply of liquid as described hereinbefore together with a peristalticpump, the extensions of the bag being configured for co-operation withthe pump whereby liquid from the bag may be pumped at a controlled ratefrom the bag to some other site.

[0013] By way of example only, some specific embodiments of liquidsupply bag arranged in accordance with the present invention will now bedescribed, reference being made to the accompanying drawings, in which:

[0014]FIG. 1 is a plan view of a first embodiment of bag;

[0015]FIG. 2 is an edge view on the bag of FIG. 1;

[0016]FIG. 3 illustrates peristaltic pump members engaged with the tubeof the extensions of the bag of FIGS. 1 and 2,

[0017]FIG. 4 is a plan view of a second embodiment of bag; and

[0018]FIG. 5 is a plan view of a third embodiment of bag.

[0019]FIGS. 1 and 2 show the first embodiment of bag in its normalorientation, when the bag is to be used for the supply of a containedliquid to a patient. The bag 1 comprises two sheets of medically stableplastics material 10, 11, each of the same shape and with their edgesbonded together so as to define a main portion 12 within which liquid iscontained before its supply to a patient. At the upper end of the bagthere is a carrying handle 13 formed integrally with the bag and asuspension hanger 14 by means of which the bag may be positioned on ahook provided on a stand or frame, in a manner known in the art, forarrangement adjacent a patient. Thus, the bag may be disposed above apatient, as is conventional with gravity feed, or on the same level oreven below a patient, since the liquid is to be pumped from the bag, ata constant head.

[0020] Below the main portion 12 of the bag, each of the side sheets 10,11 has a generally rectangular extension 15. Between those extensions 15there is defined a passageway 16, by suitably bonding together the twoextensions. Preferably, one of the extensions is flat, even where thepassageway 16 is present, and the other sheet, as considered incross-section, is convexly curved in the region of the passageway thoughflat elsewhere. In this way the passageway formed has a D-shapedcross-section. As shown, that passageway has a generally linear firstportion 17 leading from the bottom of the main portion of the bag andopening into a part-circular second portion 18 of constant radius andextending for a little less than 360°, say 300° to 340°, so as to have aC-shape. The circular second portion 18 then leads into a furtherpart-circular third portion 19, extending around the outside of one-halfof the circular second portion 18 in the opposite direction thereto.That third portion 19 leads into a linear fourth portion 20 running tolower edge 21 of the extensions, remote from the main area of the bag. Apipe connecting spigot 22 is secured to the end of the fourth portion 20of the passageway 16, to permit the connection thereto of a conventionalintravenous catheter flexible pipe.

[0021] As shown in the drawings, the principal areas of the bag and ofthe passageway are defined by strong bonds 23 between the sheets 10 and11, which may be formed for example by thermal welding, sonic welding orRF welding. The regions of extensions 15 outside the lines of thesewelds are joined together for example by means of a simple adhesive orby a simpler welding process performed to a lower standard than thestrong bonds 23.

[0022] The extensions 15 themselves are profiled having regard to thedesign of a peristaltic pump with which the bag is intended to be used.In FIGS. 1 and 3 the extensions 15 are shown as being of lesser widththan the main portion 12. It is to be understood, however, that theycould be of the same width as the main portion 12 or a greater widththan the main portion 12. Further, those extensions include a pair ofregistration holes 24, which may locate on pegs provided on the pump, togive proper alignment between the circular second portion 18 of thepassageway 16 and the pumping members of the peristaltic pump. Inaddition, there is a central hole 25 through the extensions 15concentric with the circular second portion 18, for location on theoperating part of a peristaltic pump.

[0023] Though the walls defining the main area of the bag are integralwith those of the extensions 15, nevertheless the plastics sheets fromwhich those walls are made may be modified in order to allow the tube 16formed within the extensions to have the required properties for pumpingby means of an attached peristaltic pump. For example, the extensions 15may have a thinner wall thickness to give greater flexibility to thepassageway 16, to facilitate pumping. In the alternative, thoseextensions may have a greater wall thickness, in order to accommodatethe on-going flexing of the passageway 16 caused by operation of anattached peristaltic pump. That greater wall thickness may be achievedby laminating a second sheet with the sheet defining the main area ofthe bag together with the integral extension, that second sheet beinglaminated only over the area of the integral extension 15.

[0024] An advantage of having the passageway 16 defined by walls of agreater thickness is that the passageway may be given a measure ofresilience, to return the passageway to its original shape beforecompression by the pump members. This recovery of the passageway shapewould encourage the drawing of fluid into the passageway from the bag,so reducing the dependence on gravity feeding.

[0025] The extensions 15 may carry a label identifying the content ofthe associated bag. Such a label may include a bar-code or aprogrammable device which may then be read by a reader associated withthe pump. The read information may be displayed by a control circuitassociated with the pump, and such a control circuit could even preventthe administration of excessive doses, from information read from thelabel.

[0026]FIG. 3 shows the positioning of the extension 15 with respect tothe rotary pumping elements 26 of a peristaltic pump. The elements aremounted to roll continuously around the circular second portion 18 ofthe passageway 16, in contact with the convexly curved surface of thepassageway, thereby effecting positive displacement pumping of liquidout of the bag and along the passageway 16 to the outlet spigot 22. Thepump includes a power drive arrangement (not shown) for the pumpingelements 26, adjustable to give the required liquid flow-rate throughthe passageway 16 and into a pipe (not shown) connected to the spigot22. That flow-rate may be calculated by using the cross-sectional areaof the passageway 16 in the region of the circular second portion 18,together with the rotational speed of the pump.

[0027] An advantage of a pump arrangement as shown is that fluid cannotfree-flow through the passageway 16 from the bag. There will always beone rolling pumping element 26 closing off the passageway and drivingliquid in front of the roller, when the pump is being driven. Equally,if the pump is stopped, liquid cannot flow from a patient back to thebag. In addition, however, the passageway 16 may be provided at thedownstream end with a self-sealing closure, openable by the peristalticpump when the bag is in position in the pump.

[0028] A peristaltic pump may be made relatively simply and be of lightweight so that it may be clamped to the extensions 15 and suspended withthe bag from the hanger 14. The pump may include a self-contained powersupply for the pumping elements, or may be supplied with electricityfrom a remote power pack. One example of a suitable pump is described inour International patent application filed on even date herewith underthe title “Peristaltic Pumps”, claiming priority from UK patentapplication No. 0012930.4 which is incorporated herein by reference.

[0029] A number of modifications may be made in the bag shown in FIGS. 1to 3. One of these is shown in FIG. 4, where the bag is denoted as 101.Elements in FIG. 4 which correspond in substance to elements in FIGS. 1to 3 are given the same numerals, but with the addition of 100. As willbe seen, the bag 101 differs from the bag 1 in that the portions of thepassageway 116 are arranged in a different order to those of passageway16. Thus, the passageway 116 is formed successively of a generallylinear portion 117, a part-circular portion 119, a circular portion 118(for engagement with the pumping elements) of constant radius andextending for a little less than 360°, say 300° to 340°, and a linearfourth position 120. This may have an advantage over the passageway 16,in that it reduces the length of the portion of the passageway which isdownstream of that which is engaged by the pumping elements. This mayhelp reduce undesirable fluctuations in the pressure of the liquid as itis supplied to the patient.

[0030] A further modification is shown in FIG. 5, which illustrates abag 201. Elements in FIG. 5 which correspond in substance to elements inFIGS. 1 to 3 are given the same numerals, but with the addition of 200.The bag of FIG. 5 is distinguished by the fact that it has a pluralityof passageways 219 in parallel with one another. FIG. 5 shows twopassageways, but it is to be understood that more than two could beprovided. The main portion of the bag has two sub-portions 212 a and 212b, for separately containing two liquids, each portion 212 a, 212 bcommunicating with the upstream end of a respective one of thepassageways. The passageways themselves resemble the passageway shown inFIG. 4, and each have separate portions 217 a, 217 b and 219 a and 219b. Their circular portions 218 a and 218 b are separate at theirupstream ends but merge into a common portion 218, where the liquids mixwith one another. To assist mixing, the mixing portions 218 may beprovided with mixing means, for example in the form of protrusions 230,which induce turbulence in the liquids. Finally, there is a commonportion 220 leading to the bag outlet.

[0031] The bag shown in FIG. 5 permits the storage and delivery of twoliquids which require to be delivered together but which cannotsatisfactorily be stored together. The delivery is effected using asingle set of pumping elements, which ensures that the two liquids aredelivered in whatever may be the desired ratio, as predetermined, forexample, by the respective cross-sections of the two passageways. It isto be understood that although FIG. 5 is shown as a modification of thepassageway layout of FIG. 4, one could alternatively use a modificationof the passageway layout of FIG. 1.

[0032] Though a bag intended for containing a liquid for supply to thehuman body must be made of medical grades of plastics material and mustbe made under controlled sterile conditions, it will be appreciated thatthe bag is relatively cheap to manufacture and may be used with aperistaltic pump without any further modification. It is thus simple andeasy to use in the healthcare industry and may be regarded as adisposable item, when empty. By contrast the peristaltic pump may beused as often as is required by disconnecting it from an empty bag andreconnecting it to a fresh bag.

1. A bag for containing a liquid intended to be supplied in a controlledmanner to some other site, comprising a main bag portion having a pairof overlying side walls joined together around their edges thereby todefine a reservoir for the liquid, the side walls having a pair ofintegral overlying extensions projecting from the conjoined edges so asto form a pump area projecting from one side of the bag, the extensionsbeing bonded together to define a tube-like passageway having a sectionof part circular form and extending from the interior of the reservoirfor fluid to an outlet region at an edge of the pump area, theextensions being profiled and adapted to permit the connection theretoof a peristaltic pump device having pump members driven around acircular path centered on the centre of said section of the passageway,whereby the connection of the peristaltic pump device to the extensionsand co-operable with the passageway controls the out-flow of liquid fromthe reservoir.
 2. A bag as claimed in claim 1, wherein the passagewaycomprises successively, as considered from its reservoir end to itsdownstream end, a generally linear first portion, the part-circularsecond portion, a part-circular third portion extending round theoutside of part of the second portion, and a linear fourth portion.
 3. Abag as claimed in claim 1, wherein the passageway comprisessuccessively, as considered from its reservoir end to its downstreamend, a generally linear first portion, a part-circular second portion, apart-circular third portion, with the second portion extending round theoutside of part of the third portion, and a linear fourth portion.
 4. Abag as claimed in any of the preceding claims, wherein the outlet regionof the passageway is provided with a socket or spigot for the directconnection thereto of an intravenous catheter supply pipe.
 5. A bag asclaimed in claim 4, wherein the socket or spigot is separately formedand is bonded to the extensions to communicate with said passageway. 6.A bag as claimed in any of the preceding claims, wherein the extensionsinclude registration openings for mating with corresponding projectionsprovided on a peristaltic pump with which the bag is to be used, toobtain alignment between the passageway in the extensions and pumpingmembers of the pump.
 7. A bag as claimed in any of the preceding claims,wherein the passageway in the extensions is defined by lines of thermal,sonic or RF welding bonding together the two overlying side wallsforming the extensions.
 8. A bag as claimed in any of the precedingclaims, wherein the end of the main bag portion remote from theextensions is provided with an integral suspension hanger.
 9. A bag asclaimed in any of the preceding claims, wherein, as viewed incross-section, the passageway is defined by a flat portion of one of theextensions and a convexly curved portion of the other of the extensions.10. A bag as claimed in any preceding claim, wherein the main bagportion defines a plurality of sub-portions for separately containing aplurality of liquids, and wherein the extensions define a correspondingplurality of passageways each of which communicates at its upstream endwith a respective one of the sub-portions.
 11. A bag as claimed in claim10, wherein the plurality of passageways run substantially parallel toone another.
 12. A bag as claimed in claim 10 or 11, wherein thepassageways merge with one another before the outlet thereof.
 13. A bagas claimed in claim 12, comprising mixing means for assisting mixing ofthe liquids after the passageways have merged.
 14. The combination of abag as claimed in any of the preceding claims and a peristaltic pump,the extensions of the bag being configured for cooperation with the pumpwhereby liquid from may be pumped from the bag at a controlled rate.